1. Field of the Invention
The present invention relates to a work mounting apparatus for mounting an IC chip or some other electronic component, as a work, on a printed board.
2. Description of the Related Art
As one such work mounting apparatus, a continuous rotation-type apparatus is under development. This type of work mounting apparatus comprises a workbench having a work supply section and a work mounting section, a rotating drum which is continuously rotated, a large number of work heads protruding from the outer periphery of the rotating drum, and a suction nozzle protruding from the outer peripheral surface of each work head toward the workbench.
While the drum is rotating, the work head is turned about a turning axis extending in the radial direction of the drum, but its posture is held in a fixed posture during the turning motion. Namely, the suction nozzle is held in a position facing the workbench at all times despite the turn of the work head.
In this work mounting apparatus, when the work head is turning during the rotation of the drum, the suction nozzle of the work head makes cycloid motion, i.e., up-and-down motion with respect to the workbench. Thus, if the turning speed and turning direction of the work head are properly set with respect to the peripheral speed of the rotating drum, the speed of the suction nozzle of the work head relative to that of the supply and mounting sections can be made substantially zero when the nozzle is located closest to these sections. Accordingly, even while the drum is continuously rotated, if the timing for the supply and stoppage of a suction pressure with respect to the nozzle of the work head is properly controlled, the nozzle can reliably attract a work on the supply section and then mount the attracted work onto the printed board on the mounting section. Thus, the continuous-type work mounting apparatus permits continuous mounting of works on printed boards, whereby the mounting efficiency is greatly improved.
In the work mounting apparatus described above, when the turning speed of the work head is changed, the cycle of the cycloid motion of the suction nozzle also changes. Thus, by controlling the turning speed of the work head, the mounting position on the printed board at the mounting section, in which the work is to be mounted, can be shifted in the circumferential direction of the rotating drum. However, the mounting position cannot be shifted in the radial direction of the rotating drum.
When mounting works to an optional point on the printed board, therefore, the printed board must be placed, e.g., on an XY-table, so that it can be moved in the radial direction of the rotating drum by the XY-table.
If the XY-table is used, however, the work mounting efficiency is restricted by the actuating speed of the XY-table, and thus the rotational speed of the drum cannot be sufficiently increased. hindering improvement of the work mounting efficiency.